The knee joint is generally considered the largest and most complicated joint in the body. Though frequently considered a hinge joint the knee is actually two joints, lateral and medial, between femur and tibia, and one arthrodial joint between the patella and the femur. The chief movements of the knee are flexion and extension.
The flexion and extension movements of the knee joint are not simply pivotal movements about a fixed axis. During flexion, the axis around which movement takes place shifts backward, and during extension it shifts forward. This is different from a more typical hinge joint, such as an elbow, where the axis of rotation does not shift. As full extension is reached the femur is rotated inward and the joint is "locked" with the ligaments taut. The joint is, in effect, disposed in a locked position with the ligaments taut. This gives the joint greater stability in the extended position. As flexion is initiated, the femur initially lowers or moves downwardly with a small external rotation of the femur which unlocks the joint and subsequently the femur rotates or rolls about the joint to full flexion. Accordingly, the initial unlocking of the knee joint during flexion precedes actual full rotation of the knee.
A simple hinge brace generally fails to provide proper support to limit permissible rotation during the unlocking motion. For a brace to more fully support the knee joint and facilitate rehabilitation of an injured joint the brace should more closely analogize the movement of the knee than a simple hinge does. Ideally, a brace will simulate the movement of the knee joint to provide greater support and stability through the range of flexion and extension of the knee joint.
Contemporary braces generally fail to provide such precise simulation of the knee joint as described in connection with the present invention. Consequently, those devices generally provide inadequate support and possibly permit reinjury of the knee joint, even when the brace is worn. Most contemporary braces are further deficient in that the vertical plane of the brace is fixed at the time the brace is manufactured and may be unsuitable for individuals having different curvatures at the level at the knee. Such curvatures are commonly attributable to an imbalance between the medial and lateral support of the knee. Lack of adequate lateral support of the knee may produce a bowlegged condition, i.e. outward curvature at the level of the knee. A lack of medial support of the knee may produce a knock-kneed condition, characterized by an inward curvature at the level of the knee. A brace designed for individuals having normal curvature of the leg at the level the knee may therefore be uncomfortable or entirely unsuitable for bowlegged or knock-kneed persons. In recognizing this deficiency, most state of the art knee braces are manufactured on a prescription, one of a kind basis, to properly accomodate the differing physical parameters of the user. As will be recognized, such unique, one of a kind fabrication significantly increases overall cost of the knee brace as well as increases delivery time of brace to the user. Consequently, there exists a need for a brace that may be manufactured to accomodate all patients and be subsequently adjusted at the time of initial placement upon the user to support the knee joints of users having various degrees of leg curvature at the level of the knee.
In addition to the adjustability and operational deficiencies generally associated in the prior art, most prior art knee braces additionally do not permit the effective use of the knee brace in both post surgical as well as rehabilitation applications. As will be recognized, in post surgical applications, i.e. that period of time of approximately two to six weeks following reconstructive knee surgery, there is a substantial need to provide extremely firm support for the knee joint and limit hyperextension and hyperflexion of the knee. Subsequently, during rehabilitation periods it is desirable to gradually reduce the support applied to the knee by the brace to facilitate strengthening of the knee muscles and additionally allow greater extension and flexion of the knee joint. Unfortunately, the current state of the art of knee braces has not adequately addressed the application of knee braces to both post surgical and/or rehabilitation applications and hence, there exists a substantial need in the art for an improved knee brace which is specifically designed and adapted to accomodate the differing considerations encountered in post surgical and rehabilitation applications.
As described below the present invention is directed to an improved brace which more closely simulates the movements of the joint to provide enhanced support of the joint. The invention is further directed to a brace that is adjustable to accommodate curvatures of the joint members at the level of the joint. These and other objects and advantages of the invention will be described below in connection with the appended drawings illustrating the presently preferred embodiments of the invention.